USDA Hardiness Zone 5a
Frost Dates for 50441 — Hampton, Iowa
NOAA 1991–2020 normals from Hampton, IA (1,105 ft), 1 miles northeast.
Updated
In Hampton, the last spring frost (32°F) is around April 29 in half of years and has passed by May 10 in nine years out of ten. The first fall frost comes around October 9, as early as September 26 one year in ten, leaving a typical freeze-free season of 162 days (NOAA, Hampton, IA).
- Last spring frost
- April 29
- First fall frost
- October 9
- Growing season
- 162 days
- Hardiness zone
- 5a
50% probability
50% probability
freeze-free, 50%
-20 to -15°F (-28.9 to -26.1°C) coldest night
- First snow
- November 19
- Last snow
- March 25
- Winters with snow
- 100%
- Snow per year
- —
median, 1991–2020
median, 1991–2020
28 of 28 observed
NOAA normal
Frost risk by date in Hampton
Half of springs at Hampton, IA see their last 32°F night by April 29; only one in ten is past it by April 15, and one in ten still has one after May 10. Planting tender crops after May 3 leaves a 30% risk of a frost on them, after May 6 20%, and after May 10 10%. The 11 days between the even-odds date and the one-in-ten date is narrower than at 88% of the 132 Iowa stations behind this site's ZIP pages.
In fall the first 32°F night comes by October 9 in half of years, as early as September 26 one year in ten, and holds off past October 22 one year in ten. A hard freeze of 28°F follows 11 days later, around October 20; in spring the one-in-ten date for 28°F is May 1, 9 days before the 32°F one. The freeze-free season lasts 162 days in a typical year, shorter than at 61% of the 132 Iowa stations; it reaches 180 days one year in ten and falls short of 144 one year in ten. On average 157 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 8 days longer, to about May 7, and return around September 30. Severe cold of 16°F or below comes every winter, usually between November 15 and March 20.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Apr 25 | Apr 30 | May 3 | May 5 | May 7 | May 9 | May 12 | May 15 | May 19 |
| 32°F | Apr 15 | Apr 19 | Apr 23 | Apr 26 | Apr 29 | May 1 | May 3 | May 6 | May 10 |
| 28°F | Apr 5 | Apr 9 | Apr 13 | Apr 16 | Apr 19 | Apr 21 | Apr 24 | Apr 28 | May 1 |
| 24°F | Mar 25 | Apr 1 | Apr 3 | Apr 6 | Apr 8 | Apr 11 | Apr 15 | Apr 19 | Apr 24 |
| 20°F | Mar 13 | Mar 19 | Mar 25 | Mar 29 | Apr 1 | Apr 3 | Apr 6 | Apr 9 | Apr 15 |
| 16°F | Mar 5 | Mar 10 | Mar 14 | Mar 17 | Mar 20 | Mar 25 | Mar 29 | Apr 1 | Apr 5 |
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F | Sep 16 | Sep 21 | Sep 25 | Sep 28 | Sep 30 | Oct 2 | Oct 4 | Oct 8 | Oct 12 |
| 32°F | Sep 26 | Sep 30 | Oct 3 | Oct 5 | Oct 9 | Oct 11 | Oct 14 | Oct 17 | Oct 22 |
| 28°F | Oct 4 | Oct 10 | Oct 13 | Oct 17 | Oct 20 | Oct 22 | Oct 24 | Oct 27 | Nov 1 |
| 24°F | Oct 17 | Oct 21 | Oct 24 | Oct 26 | Oct 29 | Oct 31 | Nov 2 | Nov 6 | Nov 11 |
| 20°F | Oct 27 | Oct 31 | Nov 2 | Nov 5 | Nov 7 | Nov 10 | Nov 12 | Nov 15 | Nov 20 |
| 16°F | Nov 3 | Nov 7 | Nov 10 | Nov 12 | Nov 15 | Nov 18 | Nov 21 | Nov 25 | Dec 1 |
Freeze probabilities 1991–2020 at Hampton, IA, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 50441 →Compare Hampton with another place →
Weather by month in Hampton
July is the warmest month at Hampton, IA, averaging 83°F by day and 62°F at night; January is the coldest at 25°F and 8°F. A freezing night is all but certain in every month from October to April (a 90% chance or more). From June to August the chance of a 32°F night stays under 10% each month. In spring, May still brings one in 42% of years.
Warmth for growing adds up to 2,824 growing degree days a year (base 50°F), fewer than at 71% of the 132 Iowa stations. 34% of them (965) have built up by the end of June, and July adds the most, 702. Precipitation totals 38.2 inches a year, most in June (6.1") and least in January (1.0"); May to September bring 62% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 25 | 8 | 1.0 | 100% | 31 | 0 |
| Feb | 30 | 12 | 1.3 | 100% | 27 | 0 |
| Mar | 43 | 24 | 2.1 | 100% | 24 | 14 |
| Apr | 58 | 35 | 4.3 | 100% | 11 | 75 |
| May | 70 | 48 | 5.3 | 42% | 1 | 298 |
| Jun | 80 | 58 | 6.1 | 0% | 0 | 579 |
| Jul | 83 | 62 | 4.7 | 0% | 0 | 702 |
| Aug | 81 | 59 | 4.2 | 0% | 0 | 628 |
| Sep | 75 | 50 | 3.3 | 20% | 1 | 391 |
| Oct | 62 | 38 | 2.5 | 99% | 10 | 124 |
| Nov | 45 | 25 | 1.8 | 100% | 23 | 13 |
| Dec | 31 | 15 | 1.6 | 100% | 30 | 0 |
Monthly normals 1991–2020 at Hampton, IA (1,105 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, Iowa Falls, IA, 16 miles south of Hampton, has a last frost 1 day earlier (April 28), a first frost 1 day later (October 10), a season 2 days longer.
When it snows in Hampton, Iowa
The first measurable snow (0.1 inch or more) in Hampton usually arrives around November 19, and the last of the season around March 25. Those are the middle dates across the winters of 1991–2020 at Hampton, IA, 1.1 miles away: half of years saw snow earlier, half later. Every one of those winters saw snow. The last 32°F night of spring typically comes 35 days after the last snow.
Planting calendar for 50441
| When | What to do |
|---|---|
| February 18 – March 4 | Start peppers and aubergines indoorsThey need eight to ten weeks under lights before they can go out. |
| March 4 – March 18 | Start tomatoes indoorsSix to eight weeks gives a transplant big enough to set fruit early. |
| April 1 – April 15 | Sow peas, spinach, lettuce, radish outdoorsThese tolerate light frost and prefer to germinate in cool soil. |
| April 29 onward | Transplant tomatoes, peppers, basil, squash, cucumbersThe average last freeze has passed — still watch the actual forecast. |
| by July 17 | Sow the autumn crop of carrots, beets and brassicasThey need about twelve weeks to size up before growth stops. |
| by September 25 | Harvest tender crops, or be ready to cover themA first freeze two weeks early is well within normal variation. |
| October 9 onward | Plant garlic, mulch beds, lift tender bulbsGarlic wants a cold spell; bare soil loses structure over winter. |
The weeks before and after the 50% dates are general rules of thumb, not NOAA figures; a seed packet gives the timing for each variety.
Where these figures come from
ZIP 50441 is 1 mile from Hampton, IA, which stands at 1,105 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. The 2023 USDA Plant Hardiness Zone Map lists ZIP 50441 in zone 5a, the band where the coldest night of the year averaged -20 to -15°F (-28.9 to -26.1°C) over 1991–2020; a zone describes winter lows, not frost dates.
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.